“Silicon Light Modulator” (SLM) is a term used to describe display devices that include a layer of liquid crystal (LC) sandwiched between a reflective electrode and a transparent top plane. The electrode and the layer of LC are organized as an array of pixels. When a voltage is changed on a pixel of the electrode, liquid crystals in the LC layer change their orientation and allow varying amounts of light to pass through. Each pixel can be controlled separately, and large displays can be made from large pixel arrays. Example SLMs are manufactured by Three-Five Systems Inc. of Tempe, Ariz.
Individual pixels in SLMs can be controlled by voltages that are generated using digital data. When 8 bits of digital data are used to control a single pixel, a gray scale with 256 levels can be created for each pixel. Memory devices such as random access memories can be used to hold digital information to influence the display. For example, a Static Random Access Memory (SRAM) device can be used to hold eight bits of information for each pixel in an array, and create 256 levels of gray scale for each pixel in the array.
As display sizes increase, the size of memory storage also increases. For example, a display having a resolution of 1280×1024 has approximately 1.3 million pixels, and the memory for storing pixel information is similarly large. Performance can be improved and costs of production can be lowered by coupling large memories more closely with the display devices that they drive, but one problem with coupling large memories too closely with display devices is that large memories often have defects introduced during manufacture. If a defective memory is coupled too closely with a display device, the display device may have to be discarded along with the defective memory after the memory defect is discovered.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for improved memories and display devices that can be closely coupled.